FIELD OF THE INVENTION
This invention relates to multi-cylinder, two-stroke engines of the type comprising at least one set of two cylinders, each such cylinder having a working part of the smaller diameter and a pumping part of larger diameter; a piston slidably reciprocable in each cylinder and having a working part which slides in the working part of the cylinder and a pumping part which slides in the pumping part of the cylinder; and transfer passage means between the pumping part of each cylinder of the or each set and the working part of the other cylinder of the set so that, in the or each set, at least the air for each charge required by the working part of each cylinder of the set is pumped, during operation of the engine to such working part along transfer passage means from the pumping part of the other cylinder of the set, the piston motion within the cylinders of each set being such that the pistons are 180.degree. out of phase, i.e., each piston of the set is at outer dead-centre when the other piston of the set is at inner dead-centre.
Hereinafter, engines of the above type are referred to as being "of the type specified".